See picture. Red arrows. No holes in this block either or I am missing something? A properly drilled head should work.
With the 261 Rochester B you basically have to check all the parts to make sure they are correct. The collage is of things to look at to ID what you have. My B rebuild was cold natured. Ran okay warmed up. I swapped out for a Carter YF 2100s. Excellent carb but you can tell that a least little bit is missing on the top end hence the need for a carb with a littler more flow.
I wouldn't take the big fitting out of the old intake for fear of cracking the old brittle cast iron. If it where a must, I would heat the manifold a lot to expand then fingers crossed it works okay. You can also find equivalent plumbing for the Offy. If you plan to do engine work that requires break-in, I would have a known good carburetor setup to use. Too many unknowns can happen at the same time.
I had a draft tube from a 1957 235 that sludged badly. Didn't have a PVC system. I ran solvent through it but still sludged. A torch to get it going. Placed in a metal drum. It burned itself out after about an hour. Clean as a whistle. Engine ran a little better. Less oil leaks afterwards.
Last edited by buoymaker; 06/17/20228:54 PM.
"Adding CFM to a truck will only help at engine speeds you don't want to use." "I found there was nothing to gain beyond 400 CFM."
